We will utilize a mouse TSH-secreting pituitary tumor as a model system in order to investigate at a molecular level the regulation of the biosynthesis of the alpha and beta subunits of TSH. mRNA extracted from the tumor will be translated in cell-free and whole cell systems to learn whether TSH subunits are independently synthesized from separate mRNAs. Complementary DNA probes will be synthesized after purification of mRNAs for alpha and beta TSH. The site of action of hormonal agents, such as thyroid hormones, TRH, glucocorticoids, and estrogens affecting TSH production, will be determined; transcription or processing of RNA, peptide synthesis, or post-translational modifications such as glycosylation. The role of glycosylation of the subunits of TSH in alpha-beta interaction, secretion from the cell, and target organ receptor binding will be evaluated. The development of a TSH-secreting permanent cell line will be undertaken using somatic cell hybridization techniques to facilitate studies of TSH regulation. Similar studies will be performed using human malignancies ectopically secreting alpha subunits in order to gain further understanding of the mechanisms involved in the non-random derepression of the genes for alpha or hCG-beta rather than the pituitary beta subunits.